Eduardo Habkost <ehabk...@redhat.com> writes:
> On Mon, May 06, 2019 at 01:53:28PM +0200, Markus Armbruster wrote:
>> Eduardo Habkost <ehabk...@redhat.com> writes:
>>
>> > This series adds a new CPUClass::class_name_format field, which
>> > allows us to delete 16 of the 21 *_cpu_class_by_name() functions
>> > that exist today.
>>
>> Which five remain, and why?
>
> alpha_cpu_class_by_name:
> * Translates aliases based on alpha_cpu_aliases;
> * Falls back to "ev67" unconditionally
> (there's a "TODO: remove match everything nonsense" comment).
>
> cris_cpu_class_by_name:
> * Translates "any" alias to "crisv32" if CONFIG_USER_ONLY.
>
> ppc_cpu_class_by_name:
> * Supports lookup by PVR if CPU model is a 8 digit hex number;
> * Converts CPU model to lowercase.
>
> superh_cpu_class_by_name:
> * Translates "any" alias to TYPE_SH7750R_CPU.
>
> sparc_cpu_class_by_name:
> * Replaces whitespaces with '-' on CPU model name.
I'm of course asking because I wonder whether we can dumb down this CPU
naming business to something simpler and more regular.
Let's review what we have.
For all <TARGET> in target/*:
* arm i386 lm32 m68k mips moxie openrisc riscv s390x s390x tricore
unicore32 xtensa
CPU type name format is <TARGET>_CPU_TYPE_NAME("%s"), which boils down
to:
- arm lm32 m68k moxie riscv s390x tricore unicore32 xtensa
"%s-<TARGET>-cpu"
- openrisc
"%s-or1k-cpu"
- i386
"%s-x86_64-cpu" #ifdef TARGET_X86_64
"%s-i386-cpu" #else
- mips
"%s-mips64-cpu" #ifdef TARGET_MIPS64
"%s-mips-cpu" #else
The %s gets replaced by the user's cpu model.
* hppa microblaze nios2 tilegx
CPU type name format is <TARGET>-cpu. The user's cpu model seems
silently ignored.
* alpha cris ppc sh4 sparc
No format, using ->class_by_name()
- alpha
CPU type name format is "%s-alpha-cpu".
alpha_cpu_class_by_name() recognizes the full name, the full name
without "-alpha-cpu" suffix, and a bunch of aliases.
- cris
CPU type name format is "%s-cris-cpu".
cris_cpu_class_by_name() recognizes the name without the "-cris-cpu"
suffix, plus "any" as alias for "crisv32-cris-cpu" #ifdef
CONFIG_USER_ONLY (this is the default CPU type for machine
"axis-dev88"; the other machine "none" has no default).
- ppc
CPU type name format is
"%s-powerpc64-cpu" #ifdef TARGET_PPC64
"%s-powerpc-cpu" #else
ppc_cpu_class_by_name() recognizes the name without the suffix, plus
the CPU type's PVR (8 digit hex number), plus a bunch of (case
insensitive) aliases.
- sh4
CPU type name format is "%s-superh-cpu".
superh_cpu_class_by_name() recognizes the name without the suffix,
plus "any" as alias for "sh7750r-superh-cpu" (this is the default
CPU type for machine "shix"; machines "r2d" defaults to "sh7751r",
and "none" has no default).
- sparc
CPU type name format is
"%s-sparc64-cpu" #ifdef TARGET_SPARC64
"%s-sparc-cpu" #else
sparc_cpu_class_by_name() recognizes the name without the suffix,
mapping any spaces in the user's cpu model to '-'.
Observations:
* The CPU type name format is generally "%s-T-cpu", where T is either
<TARGET> or <TARGET>64.
Exceptions:
- openrisc, sh4 uses or1k, superh instead. Looks pointless to me.
- i386 uses x86_64 instead of i38664. Makes sense.
- hppa, microblaze, nios2 and tilegx use CPU type name format "T-cpu",
ignoring the user's cpu model. These exceptions looks pointless to
me.
* The user's CPU model is generally the "%s" part of the format.
Exceptions:
- alpha additionaly recognizes full type names. If that's useful for
alpha (I'm not sure it is), why isn't it useful for all other
targets?
- cris and sh4 additionaly recognize an "any" alias, cris only #ifdef
CONFIG_USER_ONLY.
Until PATCH 4, arm also recognizes an "any" alias #ifdef
CONFIG_USER_ONLY. PATCH 4 drops that, because it's redundant with
the "any" CPU, which is a copy instead of an alias. Sure we want to
do have different targets do "any" in different ways?
See aliases below.
- ppc additionaly recognizes PVR aliases and additional (case
insensitive) aliases. Feels overengineered to me. See aliases
below.
- sparc additionally recognizes aliases with ' ' instead of '-'.
Feels pointless to me. See aliases below.
* What about deprecating pointless exceptions?
* Aliases
We have several targets roll their own CPU name aliases code.
Assuming aliases are here to stay (i.e. we're not deprecating all of
them): what about letting each CPU type specify a set of aliases, so
we can recognize them in generic code?
